The present invention relates to an air feeding device for an endoscope to feed air into body cavity.
Conventionally, an air feeding device for an endoscope has been known. The air feeding device has an air compressor which compresses the air within a sealed space, and by opening/closing a valve connected to the sealed space, the air is fed to the human body cavity through a tube such as a forceps channel of an endoscope. In such an air feeding device, in order to measure the pressure of the air, a Y-shaped tube is provided to branch off a path of the air, and a pressure gauge is connected to the branched path. It is known that, if the length of the tube extending inside the human body cavity and the length of the tube extending toward the pressure gauge are made substantially the same, the pressure of the air discharged from the channel of the endoscope toward the body cavity can be detected accurately by the pressure gauge connected to the Y-shaped tube.
When the pressure of the discharged air (hereinafter, referred to as a discharge pressure) is to be changed, the pressure in the sealed space should be adjusted so that the desired discharge pressure is obtained. In the conventional air feeding device, in order to measure the discharge pressure, the air should actually be discharged. Therefore, the pressure within the sealed space should be adjusted by comparing the, actual discharge pressure with a desired discharge pressure (i.e., a target discharge pressure to be achieved). Due to such a configuration, it is impossible to set the pressure within the sealed space to a value corresponding to the desired discharge pressure in advance, and a large amount of air is discharged uselessly until the actual discharge pressure is adjusted to be a desired value. Further, since the Y-shaped tube is used and the amount of discharged air is increased, once the pressure in the sealed space is reduced, it takes time to raise the pressure in the sealed space.